Selecting data in pandas
Python for R Users
Daniel Chen
Instructor
Manually create DataFrame
df = pd.DataFrame({
'A': [1, 2, 3],
'B': [4, 5, 6],
'C': [7, 8, 9]},
index = ['x', 'y', 'z'])
print(df)
A B C
x 1 4 7
y 2 5 8
z 3 6 9
df = pd.DataFrame({
'A': [1, 2, 3],
'B': [4, 5, 6],
'C': [7, 8, 9]},
index = ['x', 'y', 'z'])
df
A B C
x 1 4 7
y 2 5 8
z 3 6 9
df['A']
x 1
y 2
z 3
Name: A, dtype: int64
df.A
x 1
y 2
z 3
Name: A, dtype: int64
df[['A', 'B']]
A B
x 1 4
y 2 5
z 3 6
Subsetting rows
- Row-label (
loc) vs row-index (iloc) - Python starts counting from 0
Subsetting rows .iloc
df
A B C
x 1 4 7
y 2 5 8
z 3 6 9
df.iloc[0]
A 1
B 4
C 7
Name: x, dtype: int64
df.iloc[[0, 1]]
A B C
x 1 4 7
y 2 5 8
df.iloc[0, :]
A 1
B 4
C 7
Name: x, dtype: int64
df.iloc[[0, 1], :]
A B C
x 1 4 7
y 2 5 8
Subsetting rows .loc
df
A B C
x 1 4 7
y 2 5 8
z 3 6 9
df.loc['x']
A 1
B 4
C 7
Name: x, dtype: int64
df.loc[['x', 'y']]
A B C
x 1 4 7
y 2 5 8
df
A B C
x 1 4 7
y 2 5 8
z 3 6 9
df.loc['x', 'A']
1
df.loc[['x', 'y'], ['A', 'B']]
A B
x 1 4
y 2 5
Conditional subsetting
df[df.A == 3]
A B C
z 3 6 9
df[(df.A == 3) | (df.B == 4)]
A B C
x 1 4 7
z 3 6 9
Attributes
df.shape
(3, 2)
df.shape()
--------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-17-0e566b70f572> in <module>()
<hr />-> 1 df.shape()
TypeError: 'tuple' object is not callable
Let's practice!
Python for R Users
